US2647239A - Passive four terminal network for gyrating a current into a voltage - Google Patents

Description

y 8, 1953 B. D. H. TELLEGEN PASSIVE FOUR TERMINAL NETWORK FOR' GYRATING A CURRENT INTO A VOLTAGE Filed March 6, 1948 E i L L dz FIG. 3b

FIG. 30

l/WE/VZOR.

BERNARDUS D. H. TELLEGEN AGE/VT Patented July 28, 1953 UNITED STATES PATENT 1 OFFICE PASSIVE FOUR TERMINAL NETWORK FOR GYRATING A CURRENT INTOA VOLTAGE Bernardus Dominicus Hubertus-Tellegen, Eindhoven, Netherlands, a'ssignor to Hartford National Bank and Trust Company, Hartford,

Conn., as trustee Application March 6, 1948, Serial No. 13,506

In the Netherlands April 29, 1947 For the impedance elements connected between the terminals of a passive electrical quad- 4 Claims. (01. 333-24) ripole or four terminal network use has hitherto wherein the coeificient n is the transformation ratio if the positive voltages and currents correspond to those indicated with the quadripole according to Fig. 1 as described more fully hereinafter'.

The properties of quadripolesbuilt up from such network elements may be summarised as follows: a. The relations between the currents passing through and the voltages set up across the primary and secondary terminals may be represented by linear differential equations.

2). The coeflicients of these differential equations are constant; if the electrical oscillations are assumed to be sinusoidal and if for the voltage and the current at the primary and secondary terminals of the quadripole the complex magnitudes V1, I1 and V2, I2 respectively are introduced, we find as solution of the differential equations between these magnitudes the 'rela-,. tions:

' V1=Z11I1+Z12I2 V2=Z21I1+Z22I2 I (2) the four pole parameters, Z11, Z12, Z21 and Z22 being functions of frequency.

c. The quadripole cannot supply energy.

d. Between the coefiicients of the above quadripole equations there exists the soecalled reci-.

procity relation:

' Z 12 =Z21.,.. ..W

The invention has for its object to provide, in addition to the aforesaid-network elements, a fifth network element the properties of which conform to'the properties of theother elements, save that the property of reciprocity mentioned in the above underd is absent. The fifth circuit element has the property'of gyrating a current into a voltage and vice versa. In the ideal case for this fifth element the following relations exist between the-instantaneous values of the voltage set up across and the current passing through the primary and secondary terminals:

respective if the positive directions are again assumed to be in accordance with the quadripole shownin Fig. l, the coefficient s having the dimension of a resistance.

A network element to which these equations 4 apply, will be referred to hereinafter as ideal gyrator. An ideal gyrator consequently exhibits in contrast to the relation (3) the property that the anti-reciprocity Z12=Zz (5) applies.

In addition to the properties mentioned above under a, b and c, of which thelatter may be represented by the equation,

are satisfied. ,Herethe proportionality-factor y'X has the same sign, in .contradistinctionto'the relations (4), in which'the proportionality factor (5). is of opposite sign." Such 'networksconse-' quently. satisfy thereciprocity relation (3) "and drawing wherein:

Fig. 1 is a schematic dia ram illustrating the theory underlying the invention.

Fig. 2 is a first preferred "embodiment" or a gyrator element in accordance: with .gthe invention, i

Fig. 3 is a schematic diagrams-illustratingthe method of producing a medium for a gyrator,

Fig. 4 is a second preferred:embodiment pf a gyrator element in accordance"witlfithaainiaen tion, and

Fig. 5 is a band-pass filter employing a-gyrator element in accordance with the invention. S The,manner in whicma gwratmr according to the -;invention -may, be ;-reali zed is explained with reference -t0*;-

; -1. Let us -assume that the volta e 1.1 andth i ur n 1. 1.; a :Primary 4 other by means of one of these properties of the medium constituting the four-pole, this four-pole will be of a certain type.

In the first place this four-pole will or will not satisfy the reciprocity relation. To investigate this we differentiate the Equations ('7) with respect to t. The left-hand sides will then become da:/di',- etc. and dJx/ zit;- ,et c. and the right-hand ts-ides weamay multiplylmywa'w. .iNow dP/dt is a part of a current, dJ/dt is a part of a voltage,

is a part of a voltage, and H is a part of a current. So, hea ring in mind what has been rsaid-with', reference to Equations (3) and (5) about'the waythe reciprocity relation is ex- ,pressed by equality p1: opposite equality of certain :ffifl 'epole icioeificients, we see that those fourspoles: ofswhichxthe terminal pairs are coupled to each othenby-Ineans of the property of the medium .,repre s ent ed by K, 6, or x, respectively by {terminals l-q-lpf-the quadripolesshowniin Fig.1 9

produce-an-electric;field=having a field strength and: a-magnetic field having a field strength H1 whereas the. Itage Yi-and the current 12 at the-secondary;terminalssi l.of the quadripole E2 a -'msenti e1dr h v pa a fine-s n t .Hz (for; convenience all-these vectors areishown in the figure parallel to one another, ;lput,-;-in general, they have anarbitrary direction with respect to one another). The resultant of the 1A. v,;;pr, ,.wi 11, "respectively will not, satisfy the reciprocity relation of networks.

i Eurthermore, P and E are related to electric pairs of terminals and .1 and H to magnetic pairs. h oreyifi. a rau ierm r or; ageysrator could be r z d..-;byrmainl ne-l rvaterminal:pair a y a s foiitone of the; above mentioned 151K, properties hf a di m-couplin by is could lead.-only to a double electric transformer,

uld l ad Qn t a dou itfitr: syr ter,

v .couldlead only to antelectromagnetic;gyra tpr,

8 .could-=..1ead $01115 ito. an-cl ctrcmagneticyytransformer,

X could lead only to a double-magnetic transformer,

3' could lead only to a double-magnetic gyrator.

According to-the invention, use is -rnade of}, a medium such or, if desired, of a medium brought into a state such that ita'exh'ibits the property that at least one of:the=--coeiiicients 'y, A, or g is unequal to zero, for if this is the case, it will be possible, by a coupling as, in;:licated1 above between "primary and, aQfSQQQZQQEi-ly. electric. or magneticfield; tobui'ld upa gyrato1',-.which,.is ida'ljornearlyide'al.

Some examples f 'media'will be discussedawith reference to Figs, z and 3; o ne,p ,thesaideoefficients being here 1unequal to ,zero. Fig.4 shows" a practical example; of a gyr'ator according to the invention.

R 2 r ts a. s a ot accordinetothe i vention" in-which. f 0r,12h6' medium, use is made of asuhstancegior Whichfthta-cOffiCiRt 3 equal to zero. isuch asubstanceirnay.be'obtained by usingjior'examplefmagneticj material adapted to. he brought. into 'the'ist 'te of saturation ,by, a constant. magnetic neld 101. .low lfield strength I-Io. Theprimary terminals l have ccn'nectedto them a fwinding 4, agprimary,rnagnetic field ,of. ,field strength l-Ii being producediby the currentpassing 'throu'gh this 'winding '4. fowinglto the gyromagnetic efie'ctthecombination or this alternating field H1 and theifield Ho, produces, at right angles to these twoffields at-magnetic alternating field Hz which induces in'the winding connected tothe secondary terminals 2 a voltage which is proportional :to rthecurrenusuDDhedto the :primary terminals I. In order-to guaranteeanwptimumi'ideal' gyratoreifect, it-isf desirable; that theImutual induction betweeri the coils" land 1 urinal zpairsi-pna four-pale.are coupled to eacli' Fig. 3a illustrates, by way of" example, a method of manufacturing a medium 3 for which the coefficient :y is unequalto zero. For

.this purpose a suspension of magnetic material is made in a carrier liquid in which, moreover, an oversaturated solution of a material having a high electrical dipole moment is formed. This film of electric dipole material will now beform'ed around the magnetic dipoles 5 the magnetic and electric polarities having the same or opposite sense. If a medium 3, built up from such a magnetic material wherein the elementary magnets have at the same time a great magnetic dipole moment and, parallel thereto, a permanent electric dipole moment, is brought between the poles of a magnetic circuit 6, a magnetic fiux will be produced in the circuit 6, if a current is supplied to the electrodes 8 connected to the primary terminals I, owing to which the winding 1 connected to the terminals 2 has induced in it a voltage which is proportional to the current supplied to the primary terminals I.

A circuit-arrangement in which the medium has a coefficient which is unequal to zero, may be constructed, for example, in a manner similar to that shown in Fig. 2, the coils 4 and 1 being replaced by condenser plates.

The invention is not considered to be restricted to gyrators comprising media of which only one of the coefiicients 'Y, A or is unequal to zero; it is possible that at the same time more than one of these coefficients is unequal to zero. Moreover, some of the coefiicients K X or a will, in general be unequal to zero.

A general property of a quadripole built up with a gyrator is that Z12 is unequal to Z21.

Fig. 4 shows one example of application of a gyrator according to the invention. The primary terminals I of the gyrator 3 are connected to an oscillatory circuit I2 tuned to the central frequency of electrical oscillations to be transmitted, whereas the secondary terminals 2 are connected to a similar oscillatory circuit I3. The lower terminal I and the lower terminal 2 are connected to a point of constant potential, and the upper terminals I and 2 are interconnected for direct-current through a coupling impedance M. It has now been found to be possible to dimension the direct-current coupling impedance l4 and the gyrator coupling 3 in such manner with respect to one another that the circuit behaves like a bandpass filter. If in this case the gyrator coupling has the correct sign with respetc to the direct-current coupling, so that the two couplings support one another, it has been found that with a similar bandwidth and with similar input and output impedances as with a conventional bandpass filter comprising inductively or capacitatively coupled circuits, the transmission ratio is, with critical coupling, a factor l-|- /2 as great.

If the quadripole shown in Fig. 2 is used as a gyrator, use may be made in a suitable manner of the coils 4 and I for the inductances included in the circuits l2 and 13.

What I claim is:

1. A passive network comprising a polarized medium, input means to supply an alternating voltage V1 to said medium to produce an alternating current flow I1 in said input means, output means coupled to said medium to obtain an alternating voltage V2 producing a current flow Is in said output means, said medium possessing gyroma netic characteristics and including rnaterial having an anisotropic polarization property wherein: .V1=-.'SI2.

Where S is a-constantfl 2. A passive four-terminal network comprisinga polarizable medium possessing gyromagnetic properties, input terminals to apply an input voltage and an input current to said network, output terminals to take an output voltage and an output current from said network, means to polarize said medium in a firstdirection, means connected to said input terminals to produce a primary field in said medium in a second direction different from said first direction, said primary field producing in said polarized medium a secondary field having a third direction difierent from said first and second directions, and means coupled to saidsecondary field to produce said output voltage and output current at said output terminals.

3. A circuit arrangement having a passive four-terminal network comprising a polarizable medium possessing gyromagnetic properties, input terminals to apply an input voltage and an input current to said network, output terminals to take an output voltage and an output current from said network, means to polarize said medium in a first direction, means connected to said input terminals to produce a primary field in, said medium in a second direction different from said first direction, said primary field producing in said polarized medium a secondary field having a third direction different from said first and second directions, and means coupled to said secondary field to produce said output voltage and output current at said output terminals, the relation between said input voltage V1, said input current I1, said output voltage V2 and said output current 12 being wherein Z11 is the input impedance of the network, Z22 is the output impedance of the network and Z21 and Z12 are transfer impedances having unequal magnitude.

4. A passive four terminal network comprising -a polarized medium possessing gyromagnetic properties, said medium being polarized in a, first direction, input terminals to apply an input voltage and an input current to said network, output terminals to take an output voltage and an output current from said network, means connected to said input terminals to produce a. primary field in said medium in a second direction difierent from said first direction, said primary field producing in said polarized medium a secondary field having a third direction different from said first and second directions, and means coupled to said secondary field to produce said output voltage and output current at said output terminals.

BERNARDUS DOMINICUS HUBERTUS TELLEGEN.

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2,379,168 McClellan "Jun26;1945 5? H 2383475 Dodington Aug. 28, 1945 Holstem et aL, Physlcal Revlgw, 101 118,- De- 2 464 807 Hansen 7 Mar. 22 1949 Q5 .cember-15', 1940, pp. 1098-1113. "(Copy m-Smengtific Library.)

iGrifliths, Nature, Vol. 158, 'November 9,'1946, "pp; 1670-671. (Copy in Scientific Library.)

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